init

node_modules/@sentry-internal/tracing/esm/browser/web-vitals/onTTFB.js

@@ -0,0 +1,92 @@
+import { WINDOW } from '../types.js';
+import { bindReporter } from './lib/bindReporter.js';
+import { getActivationStart } from './lib/getActivationStart.js';
+import { getNavigationEntry } from './lib/getNavigationEntry.js';
+import { initMetric } from './lib/initMetric.js';
+
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Runs in the next task after the page is done loading and/or prerendering.
+ * @param callback
+ */
+const whenReady = (callback) => {
+  if (!WINDOW.document) {
+    return;
+  }
+
+  if (WINDOW.document.prerendering) {
+    addEventListener('prerenderingchange', () => whenReady(callback), true);
+  } else if (WINDOW.document.readyState !== 'complete') {
+    addEventListener('load', () => whenReady(callback), true);
+  } else {
+    // Queue a task so the callback runs after `loadEventEnd`.
+    setTimeout(callback, 0);
+  }
+};
+
+/**
+ * Calculates the [TTFB](https://web.dev/time-to-first-byte/) value for the
+ * current page and calls the `callback` function once the page has loaded,
+ * along with the relevant `navigation` performance entry used to determine the
+ * value. The reported value is a `DOMHighResTimeStamp`.
+ *
+ * Note, this function waits until after the page is loaded to call `callback`
+ * in order to ensure all properties of the `navigation` entry are populated.
+ * This is useful if you want to report on other metrics exposed by the
+ * [Navigation Timing API](https://w3c.github.io/navigation-timing/). For
+ * example, the TTFB metric starts from the page's [time
+ * origin](https://www.w3.org/TR/hr-time-2/#sec-time-origin), which means it
+ * includes time spent on DNS lookup, connection negotiation, network latency,
+ * and server processing time.
+ */
+const onTTFB = (onReport, opts) => {
+  // Set defaults
+  // eslint-disable-next-line no-param-reassign
+  opts = opts || {};
+
+  // https://web.dev/ttfb/#what-is-a-good-ttfb-score
+  // const thresholds = [800, 1800];
+
+  const metric = initMetric('TTFB');
+  const report = bindReporter(onReport, metric, opts.reportAllChanges);
+
+  whenReady(() => {
+    const navEntry = getNavigationEntry() ;
+
+    if (navEntry) {
+      // The activationStart reference is used because TTFB should be
+      // relative to page activation rather than navigation start if the
+      // page was prerendered. But in cases where `activationStart` occurs
+      // after the first byte is received, this time should be clamped at 0.
+      metric.value = Math.max(navEntry.responseStart - getActivationStart(), 0);
+
+      // In some cases the value reported is negative or is larger
+      // than the current page time. Ignore these cases:
+      // https://github.com/GoogleChrome/web-vitals/issues/137
+      // https://github.com/GoogleChrome/web-vitals/issues/162
+      if (metric.value < 0 || metric.value > performance.now()) return;
+
+      metric.entries = [navEntry];
+
+      report(true);
+    }
+  });
+};
+
+export { onTTFB };
+//# sourceMappingURL=onTTFB.js.map